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Study Of Optical Fiber High Temperature Measurement Technology And System Based On Blackbody Cavity Characteristics

Posted on:2011-12-21Degree:DoctorType:Dissertation
Country:ChinaCandidate:L L CaiFull Text:PDF
GTID:1118360302494406Subject:Detection technology and automation equipment
Abstract/Summary:PDF Full Text Request
Temperature is one of the most important physical quantities determining the state of matter. The basic rules, researched in the disciplines of thermodynamics, hydromechanics, heat transfer theory, physics, chemistry, and metallurgy, have the close relation with the temperature. So temperature measurement and control play very important roles in the national defense, military, scientific experiments, industrial and agricultural production. With the development of science and technology, a number of common temperature measurement technologies, such as contact temperature measurement technology and the non-contact ones, have been unable to meet the needs of scientific and technological development. Hence, researches on the thermometer principle and multi-spectral radiation temperature measurement technology are the important direction at home and abroad. This paper mainly studies fiber high temperature measurement system theoretically and experimentally, which is based on blackbody cavity characteristic.According to the blackbody radiation heat transfer principle, this paper established the mathematic model of blackbody cavity sensor integrated emissivity and the effective emissivity of the surface. And discuss the all kinds of equation on the angle factor and singular point distribution. Then analyze the effects of blackbody cavity geometry size versus the point distribution of effective emissivity of the surface on blackbody cavity. Based on this, we obtained the optimum parameters for the sensor selecting.The scheme of colorimetric fiber temperature measurement system is presented, which implements wavelength selection using tunable FBG filter. According to model coupling theory, the reflective spectrum of FBG is established and corresponding parameters are analyzed. In the same way, according to elastic-optic effect, the corresponding sensor model of FBG uniform stress in the axial direction is established. On this basis, the structure of FBG tunable filter is designed, and the best choice of FBG parameters are obtained.The colorimetric temperature measurement method, based on the wavelength selection, is analyzed theoretically. By comparing to the characteristic of the different radiation power and emissivity, at the same temperature the key effective parameters of radiation power are determined. The merits and feasibility of the wavelength selection colorimetric temperature measurement scheme are demonstrated. According to the noising characteristic of the measured temperature signal, the concrete process and implementation of wavelet de-noising are analyzed. At the same time, the corresponding algorithm program is designed, who's the feasibility of application demonstrated theoretically.The filter high temperature measuring system, based on the blackbody cavity characteristic, is designed. And the hardware system and software design are introduced. By stationary and dynamic experiments to the fiber radiation temperature measuring system, the reasons of the system error are analyzed simultaneously. The feasibility of denoising the dynamic temperature signal using the wavelet filter method is demonstrated by the dynamic experiment. Based on it, Optical fiber high temperature measurement system is tested by stationary and dynamic experiments.According to the researches and analysis on high temperature test system, further study and the solution question still exist.When the temperature of the black body cavity surface is non-uniform, its superficial effective emissivity of each spot has change, leading to the integral emissivity of blackbody cavity variation, namely non-uniform black body cavity surface temperature affects the integral emissivity. The black body cavity has thermal transmission in the high temperature measuring process. Researching the dynamic change characteristic of the black body cavity integral emissivity, and the material and the method of enhancing dynamic response of the black body cavity sensor are necessary.
Keywords/Search Tags:Radiation temperature measurement, Blackbody cavity sensor, Tunable FBG filter, Wavelet de-noising, Colorimetric temperature measurement
PDF Full Text Request
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